Time mechanism



J. l.. HARRIS 2,341,774

T'IME -MEGHANISM Filed Dec. 30, 1939 5 Sheets-Sheet l Feb. 15, 1944.

J. l.. HARRIS TIME MECHANISM 5 sheets-Sheet 2 Fled Dec.

Feb. 15, 1944. J. L.. HARRIS TIME MECHANISM l Filed Dec. 30, 1939 5 Sheets-Sheet 3 .i A14/4 a W1 'nvenor John@ mamlmlvrisl Glorngg 5 Sheets-Sheet 4 .J. @HARRIS TIME MEGHANISM Filed Dec. so, 1959 Feb. l5, 1944.

Feb. 15, 1944. J, HARRIS TIME MECHANISM Filed Dec. 5o, 1959 5 Sheets-Sheet 5 ,nnmtor Cmorngg Patented Feb. 15, 1944 rinvia` MEcHANisM John L. Harris, Minneapolis, Minn., assgnor .to Minneapolis-Honeywell 'Regulator Company, Minneapolis, Minn a corporation kof Dela- Ware Application December 30, 1939, Serial No. 311,799

(Cl. i4-122) 7 Claims.

My invention relates to improved forms of electrically driven timing devices adapted to be employed in combination with thermostats or the like and switches.

An object lof my invention is the Yprovision of a novel'speed reducing Vmechanism embodying relatively few parts, occupying a minimum yof space and yet capable of electing an unusually great speed reduction.

Another object of vmy invention is to provide .a speed reduction mechanism embodying gears 'driven at different speeds and reciprocatory -mechanism arranged to be operated'through one cycle in a time interval depending on the dilerence in speeds of the gears.

Another object of my invention is -to-provide a clock mechanism embodying a speed reduction arrangement wherein two gears `are driven at different speeds and a reciprocatory element is moved an amount depending on the difference in speeds of the gears, the reciprocatory element cooperating withv pawl and ratchet means to turn a time indicating rotary member.

Numerous other objects and advantages of my invention will become apparent from the :following detailed description and annexed drawings wherein:

Figure l is a front exterior view of a time controlled thermostat embodying my invention;

Figure 2 is a cross sectional sideview of the complete assembly of the thermostat and timing mechanism;

Figure 3 is aview of the motor and part of the gear train of the timing unit;

Figure 4 is a sectional view on an enlarged lscale taken along line 4-4 of Figure 2;

Figure 4a is an elevational view of a portion of vthe pawl and ratchet mechanism, the view -being on the same scale as Figure 4;

Figure 5 `is an exploded view of manual adjusting means for .adjusting the times at which the timing means automatically adjustsV the thermostat;

Figure 6 is a view Figure 5;

Figure 7 is a cross-sectional View of a complete assembly of another form of my invention;

Figure 8 is a view of another embodiment of my invention incorporated in Aa time clock, this view being taken along line 3 8 of Figure f9;

Figure 9 is a view taken along line 9--9 of Figure 8;

Figure 10 is a View of a form which the timing motor unit of my invention may take, this view of the day cam shown in -beingtaken along line lillll of Figure 1l;

Figure 11 is across-sectional view of a clock utilizing the timing motor unit of Figure 10, the view of the timing motor unit being taken along line H-H -of Figure 10;

Figure 12 is a View of another embodiment of my invention applied to a switch, this view being taken along line l2--l2 of Figure 13, .and

Figure 13 is a side view of the embodiment of Figure 12.

'Referring to the drawings, Figure l is a front view of a Vtime controlled thermostat, Vnumeral Ill designating lgenerally a vcasing enclosing the thermostatic member 'and the time clock. The casing l0 comprises a rear portion Il having openings for air circulation and in which the timing mechanism vis tlocated and a front portion l2 (see Figure 2f) which encloses the thermostatic mechanism. The casing It has a portion |3 'forming va panel having a slot i4 therein and van opening 15. `The edges ofthe slot I4 are graduated'in degrees of temperature and within -the portion I2 in linewith the slot ld there is a mercury thermometer yas shown held in position by 4suitable clips. A timing dial IE is visible `through .the opening l5 in the Vpanel I3.

The portions ll and l2 of the casing Il! vare separated by a Ypanel l1, the Ylower portion of which is bent at a right angle as seen at I8, `the casing l@ being removably secured to thisv portion by screw 9. There -is an opening in the central yportion -of the panel 'l1 andthe edges of the material Vof `the panel `l'l around this opening are anged so as to form a continuous shoulder laround the opening. In intertting engagement with this `shoulder so 4as to cover the opening in the panel Il is a piece of insulating material I9 lwhich lis attached to the panel Il by means `of rivets or the like. 'The thermostaticmechanism comprises a U- shapedbmetallic element 20, one end of which is attached by riveting or the like to a supporting bracket 2l, one end of an adjusting lever 22 being attached also to the bracket 12! between the bracket and theendfof the thermostatic element. At the other end of the thermostatic element there is attached by riveting or the like a contact lbracket 23- carrying an electrical contact 24. Also attached to this end ofthe thermostatic `element is a Arigid stop or backing member `25 for .the contact bracket, the lower end of the lbacking member 25 being bent up in the form of a U as shown to limit leftward movement of the contact bracket 23. The bracket 2| is carried on a pivot 2S which is journalled in ears extending out from the material of the panel Il. Numeral bracket carrying a contact screw 3| which is in a position to be engaged by the contact 24. The

upper end of the bracket 2| is bent as shown at 32 and attached to the bracket 2| near its upper end is a metal strip 33, this latter strip and the bent portion 32 of bracket 2| taking relative positions whereby to be actuatable by manual adjusting means for the thermostatic mechanism.

Referring now to the manual adjusting means, numeral 34 designates a shaft passing through a bearing 34a mounted in the panel |1. Attached to the left end of the shaft 34 is a day dial 35v graduated in degrees of temperature, this dial also being visible on Figure 1. Numeral 36 designates a bracket through which. the shaft 34 passes, the bracket having an ear or projection extending through the panel I1, this bracket additionally serving as a support for the shaft 34 and having a prong or finger 31 extending through an arcuate slot 38 in thedial 35, the finger 31 serving as a stop to limit rotation of the dial`35 in one direction or the other. Numeral 39 designates a spider having a plurality of flexible arms, this spider being interposed between the bracket 36 and the upper part of the panel I1 and acting to urge the dial 35 and shaft 34 in a leftward direction. Secured to the right end of the shaft 34 is a rotatable cam member 40 which may be made of plastic material and which has a cam surface 4| which is arranged to be engaged by the bent portion 32 of the bracket 2| at certain times. Rotatably engaged on the shaft 34 to the left of the member 4| is a rotatable cam member 42, this member having a night dial portion 43 and a portion 44 forming a cam surface adapted at times to be engaged by the upper end of the metal strip 33. The upper portions of the dials 43 and 35 extend through openings in the casing I as shown. Interposed between the rotatable member 42 and the bearing 34a is a spider 45. Numeral 46 designates a stop pin extending to the right from panel I1, its end being situated in an arcuate slot in the rotatable member 42 and serving to limit rotation of this element in one direction or the other. Numeral v41 designates a pointer formed of the material of panel |1 and extending upwardly and having an index marker thereon arranged to cooperate with the graduations on the dials. It will be understood that the flexibility of the spider 39 urges the dial 35 to the left and consequently causes the shaft 34 to maintain the rotatable members 40 and 42 in their proper respective relative positions. With the parts in the position shown, the strip 33 is engaging the cam surface 44 of rotatable member v42 and thus when the night dial 43 is manually adjusted the cam surface will act on the strip 33 and will adjust the position of the thermostatic element 20 about its pivot 26. As will be pointed out later, the thermostatic mechanism may be so positioned that the bent portion 32 of bracket 2| may be brought into engagement with the cam surface 4| of rotatable member 40 so that .the position of the thermostatic element may be adjusted by adjusting the day dial 35.

The timing mechanism which I employ for automatically adjusting the thermostatic mechanism will now be described. In Figure 2 the timing mechanism as shown includes an electric 'motor designated generally at 50, this motor unit being also shown separately in Figure 3. The motor unit comprises windings 5| and a more 0r less oval shaped core 52 as may be best seen in Figure 3. The core has portions 53 and 54 formloing pole pieces disposed on opposite sides of a rotor 55. Numeral 56 designates a rectangular bracket secured to the core 50 by screws, this bracket serving as a bearing to support one end r'of a shaft 51 on which the rotor 55 is mounted.

l5 The other end of the shaft 51 is supported in a needle point jewel bearing 58, the jewel being mounted in the core 50. The motor is of the magnetic type and the pole pieces and rotor each have such relative numbers of teeth so as to cause the mo-tor to rotate at a speed of 360 revolutions per minute when the windings 5U are energized with 60 cycle alternating current.

The motor unit 50 is of the self starting type, the starting mechanism including an armature 6B,

within the windings 5|. rI'he armature 60 is attached to a bell-crank lever 6| which is pivoted to an ear forming part of a bracket 62 secured to the core 52V by means of screws. The other end of the bell-crank lever 6| engages a hook 63 on the upper end of a member 64 having an ear 65 adapted to engage the teeth on the rotor 55 when the member 64 is moved vertically. Thus when the windings 5| are energized. the armature 65 is moved to the left and the bell-crank lever 6| is operated in a direction to move the member 64 downwardly whereupon the ear 65 in moving to the position shown in Figure 2 engages one of the teeth of the rotor 55 so as to start the motor. Upon deenergization of the windings 5| the mem- I ber 64 moves upwardly to be in position for the next starting operation. Numeral 66 designates a guide for the member 64 and numeral 61 designates a stop to limit movement of the bellcrank lever 6|.

which drives a pair of gears 69 and 16 as may be seen in Figure 4. The gears 69 and 1n have different numbers of teeth, for example, in this particular embodiment of the invention the gear 69 may have 30 teeth and the gear 10 may have 8l teeth. Secured to the central portion of the gear 69 is a cup 1| and secured to the central portion of the gear 1i! is a disc member 12 having a bearing portion, the cup 1| and bearing portion of disc 12 serving as means for mounting the gears 69 and 10 on a shaft 13. The left end of the shaft 13 forms a needle point mounted in a bearing in a bracket 14 secured to the core 52 by screws as shown. The right end of the shaft 13 also forms a needle point engaged in a bearing in a metal bracket 15 attached to the panel |1 by a screw and depending therefrom adjacent the opening in the panel |1. Rotatably mounted on the shaft 13 is a collar 16 having a portion of smaller diameter so that a shoulder is formed by this portion and the other portion of the collar. The collar 16 is secured to the disc 12 by a pin 11 so as to rotate therewith. Frictionally engaged within the cup 1| is a cam 18 having a helical surface which continuously engages a cam follower in the form of a pin or rod 19 which is attached to the collar 16 and which extends through the disc 12. Cam 18 has one abrupt drop off which is at the top of the cam as seen on Fig.' 4. From the foregoing it will be understood that by Mounted on the shaft 51 is a worm gear |53 reason of the .gears` G9 and 'I0 hav-ing different numbers of teeth that they lrotate at slightly different lspeeds and therefore by reason of the different speeds there will be -a relative amount of motion between cam 'I0 and cam follower TF9 dependent on the difference in speeds` That is, with the gears 69 and 10 having 80 and 8l teeth, respectively, there will be one revolution of one gear with respect to the other for every 6480 revolutions of the motor shaft 5:7. In other words, for every 6480 revolutionsv of vthe shaft 5'! there will be one revolution of thek cam T3 relative to the follower '1:9 and hence there will be one cycle of axial movement of the collar *I for every 6480 revolutions of the shaft 5l, it bei-ng understood of course that the action of the cam 'm on the follower 'l0 is to reciprocate the collar 'i5 on the shaft '93 by reason of the helical surface of the cam 18, collar 'le normally being lurged to the left as will presently be described and abruptly moving to the left when the camfollower drops oi the drop olf on cam 13.

The portion of the collar *l of smaller diameter extends through an opening in a member 80, which member is fastened to the panel il by means of a resilient brac-heter spring member 8l. The opposite end of the member 80 bent over slightly and normally engages a stop '02 on the panel Il. There rare a pair of ears 03 and 84, best seen in Figures 3 and 4a, which extend to ythe left as viewed `in Figure 4 from the inner edges of the opening in ythe member 8.0 and which are adapted to be engagedV by the shoulder of collar 'i6' when the col-lar is moved to lthe right as viewed in Figure Il. The member 80 also has a linger or projection 85 which extend-s to the right through the `opening in lthe panel vIii as may best be seen on Figure4. The finger 35 isvin effect a pawl which engages with a. ratchet `wheel 355 lmounted on a shaft Si. From kthe forego-ine: it will be seen that as the collar Z6 is reci-procated `to the right, its shoulder engages the member 80 and causes it to pivot about the sto-.p 82 with the spring member 3l flexing. When this action .occurs, the lnger or pawlii-t moves downwardly as seen on Figure 4. engages the ratchet wheel B5 and rotates,4 it in a direction which would be `counter-clockwise looking vat Fig-ure 4o. When the cam follower l0 engages the portion of cam FS permitting movement to the left, the spring member @l acting through member Sil forces the collar i6 to the left, causes `the finger 85 to be withdrawn from the ratchet Wheel $0 for the next cycle of operation. At this time, the member B0 disengagesI stop Thus for each cycle of axial movement of the collar 'i6 theratchet wheel is advanced one tooth and therefore if this .ratchet wheel is provided with 80 teeth, for example. the total speed reduction provided is 6480x550 or 518,400 to one.

The shaft 31 is supported in a bearing 33 and in a bearing formed in a bracket 019, bracket 89 having a horizontal portion seen in Fig-ure l2 and upstanding portions which maybe Sast'ened to the panel l1. the shaft 8l is secured to a collar 30 by any suitable means to which collar is secured the time dial I6 by means of a screwt'l.

With the shaft 5l rotating at a speedv of 360 revolutions per minute and with a speed reduction of 518,400 to one as described, the timing mechanism would rotate the time dial i6 one revolution every twenty-four hours. The time dial i6 has half of its surface light and graduated to designate times from 6:00 a. m. to 6:00

To the right of the bracket '39 p. m., and has the other half of its surface .dark and graduated to designate times from 6:00 p. m. to 6:00 a. m. The instrument of Figure 1 therefore indicates a time of 10:00 p, rn.

The purpose of the timing mechanism is to automatically adjust the setting of the thermostat. Secured on the shaft 3l adjacent a collar 92 is a time disc or dial 93. There are alsoa pair of segmental elements 94 and 95 having cam surfaces, the segmental elements being relatively adjustable with respect to the disc 93. For a better understanding of the elements being described reference may be had to Figure 5 which is an exploded View of these elements and the time dial I6.

As may be seen on Figure 5, the segmental elements and Q5 have iianges at their peripheries which form their respective cam surfaces, the cam surface of element 95 overlapping the cam surface of the element 9A as may be seen on Figure 4. v

The leading edge of the cam surface of the element 05 is cut off at an angle as shown at 9,6- in Figure 6. The segmental element 95 is attached to the dial 93 by a thumb screw '91 which extends through an arcuate slot 98 in the disc 93, there being a small washer on the thumb screw di to space `the element 95 from the disc 93. The element 94 is attached to the disc 93 by a similar thumb screw `0i! which passes through an arcuate slot |00 in the disc 93, there also being a small washer on screw 99 for properly spacing the element 94 and disc 93. The disc $33 has half of its surface shaded and the other half unshadedand is graduated in a manner similar to that of the time `dial i0, the shaded half of disc S3 representing times from 6:00 p. m. to 6:00 a. m. and the unshaded half of the disc representing times from 6:00 a. m. to 6:00 p. m. The elements $4 and 95 are adjustable on the shaft ai by means of loosening the respective thumb screws El and 99. By thus adjusting the elements 0d and 95', the combined extent of the cam surface of the two elements can be adjusted.`

Referring to Figures '2 and 4 it will be noted that the ylower end of the adjusting arm 22 is bent at a right angle as indicated at lill. Thus when the elements 04 and 95 are rotated in a counterclockwise direction as vseen on Figure 5, the angular portion 95 of the cam surface of element 95 will engagethe angular portion |0I of adjusting arm 22 and will move the lower end'of the arm 22 to the left so as to adjust the thermostatic .element 20 in a -clockwise direction about its pivot so as to bring the portion 32 of bracket 2l into engagement with the cam surface 4| of member di). It will be understood `that as the elements S. and 95 are rotated the portion l0! of arm 2L will first be in contact with the angular edge 96 of element $.25 and will then remain in enga-gement with the left-edge of the ilanges forming the cam 'surfaces of elements 94 and 05 until it disenr gages from the opposite end of the cam surface of element 94. With the parts in tbe position shown in Figures 2 and 4, the arm 25E just disengaged from the cam surface of element 94. The element 95 has an index-marker 02 and the element S4 has an index marker H23 and these markers are used to adjust lthe elements with respect .to the graduations en the disc S3. It Iwill also be understood that `when the lthermostatic element 20 is automatically rotated in a clockwise direction as described above the instruvment is placed on the day setting, as previously described, this setting being manually adjustable by the dial.35. In other words, when the cam surface of element 95 engages the portion IDI of arm 22, the instrument is placed on the day setting. Thus if the index marker IGZ of element 95 is adjusted to a position adjacent the numeral 5 on the shaded half of disc 99, the instrument will go on the day setting at 5 oclock in the morning. The disc 93 is of course properly relatively positioned with respect to the time dial IS so that if the element 95 is adjusted for placing the instrument on the day setting at 5 oclock in the morning as just described, at such time the disc 93 and the elements 94 and 95 will have been rotated to such a position that the leading edge of the cam surface of element 95 is just about to engage the portion IIJI of arm 22.

The position of the element 94 determines the time in the evening when the instrument will go back to the night setting. Thus if the index marker |93 on the element 94 has been placed adjacent the numeral 9 on the shaded half of the disc 93 the instrument will go on the night setting at 9 oclock in the evening. In other Words, under these circumstances at 9 oclock in the evening the disc 93 and the elements 94 and 95 will have been rotated to such a position that the portion IOI of arm 22 is just about to drop off the cam surface of element 94.

Referring now to Figure 7 of the drawings wherein I have shown another modification of my invention, numeral I9 designates generally an instrument similar to that of the previous embodiment but incorporating various different features which will now be described. In this gure numeral 29 designates a wall or partition of a building, this wall or partition having an opening therein forming a recess in which is received a portion II of the casing housing the different parts of the instrument. The other portion I2 of the casing houses the thermostatic mechanism` and is disposed on the surface of the wall as shown. The portion II `has ears or brackets I3 and I4 which provide for fastening the instrument to the wall by means of screws as shown. The casing portion I I forms a housing for the timing mechanism as in the previous embodiment. The timing mechanism comprises generally a motor unit 59 which is substantially the same as in the previous embodiment and therefore need not be described again. However, in the present embodiment the reciprocable collar I6 is connected to a push rod I8 which extends through an opening in a bracket I1. Numeral I9 designates a piece of insulating material which forms a partition insulating the casing portion II from the portion I2 of the instrument. The push rod I8 extends through an opening in the insulating material 22 and engages a pivoted element 8D which is pivoted to an ear 99. The element 89 is urged against the push rod I8 by a coil'spring 9|. Integrally formed with the element 80 is a projection or finger 92 which acts as a pawl in cooperation with the ratchet wheel 85, the ratchet wheel 89 being disposed within the casing portion I2, and there being a portion of the ratchet wheel protruding through an opening in the left wall'of the casing portion I2 as shown. The ratchet wheel 86 is mounted on a shaft which shaft is supported in a bracket 28 upstanding from the lower part of the housing portion I2. On the shaft 21 is a bevelled pinion gear 29 which drives another bevelled gear 93 on a shaft 94 ywhich drives the time dial I Ii corresponding to the time dial of the previous embodiment. The shaft 94 is supported by a 34 designates a cam driven by the shaft 21 which cooperates with the lower end of the adjusting arm 22 corresponding to that of the previous embodiment, the adjusting arm 22 having an angular portion IUI at its lower end similarly to that of the preceding embodiment. rI'he thermostatic element 20 is substantially the same in the present embodimentl as in the preceding embodiment and carries an electrical contact blade 23 having a contact 24 cooperable with a fixed contact screw 3| carried by a bracket 30 the same as in the previous embodiment. Numeral 25 indicates a rigid backing member for contact blade 23.

The present embodiment operates substantially the same as the preceding form of the invention, the cam 34 acting to move the adjusting lever 22 so as to adjust the instrument between its day and night settings. The present form of the invention has the advantage of making the apparent size of the instrument no larger than thermostats of the ordinary type not employing timing mechanism. In the present form of the invention the timing mechanism is located behind the thermostat itself and is concealed in a recess in the wall so that the casing portion I2 is the only visible part of the instrument and as stated above may have a very small size.

Figures 8 and 9 represent another form of my invention wherein my improved timing mechanism is applied to a direct reading type of clock. In Figure 8 the timing unit is disposed within a casing II having a glass window I2 in the side, the glass being held in place by suitable brackets and screws as shown. The timing unit is Very similar to that of the embodiment of Figures 2, 3 and 4 comprising windings 5I and a core 52 including pole pieces 53 and 54. The rotor as indicated at 55 drives a worm gear 68 mounted on a shaft 51, the shaft 51 being supported by the core 52 and a suitable bracket I3 as may be seen on Figure 9. The worm gear 68 drives a pair of gears 69 and 10 the same as in the rst embodiment. In the present embodiment the collar 1-6 acts on a pivoted lever 80, the lever being pivoted to an arm 82 secured to the core 52 by means of riveting or the like. Disposed between the opposite end of the lever 80 and the core 52 is a U-shaped leaf spring 8l which must be compressed when the collar 16 urges the lever 80 in a clockwise direction about its pivot. Attached` to the lever 80 is a pawl 85 cooperating with and arranged to operate a ratchet Wheel 86 on a shaft 81. In the present embodiment, as may be seen, the abrupt leftward movement of lever 80 and pawl -85 acts to rotate ratchet wheel 86 an increment at a time with a snap movement, atension beingV of course gradually built up in leaf' spring 8I as collar 16 moves to the right.

The motor of the present embodiment has 12 poles and rotates at a speed of 600 revolutions per minute. The gears 69 and 19 have 24 and 25 teeth, respectively. so that the speed reduction produced will be 24 25 or 600 to 1, that is for 600 revolutions of worm gear 68 there will be one revolution relatively of gears 69 and 19 and one axial cycle of collar 1B. It follows therefore that inasmuch as worm gear 68 is rotating at a speed of 600 revolutions per minute there will be one cycle of pawl 85 each minute. In the present embodiment ratchet wheel 86 has 10 teeth so that aggrave it will be advanced one increment per, minute thereby making one revolution in 10 minutes.

The time indicating mechanism is shown in Fig. 9, this mechanism being of the speedometer type which is well known in the art in counters, etc., and the details of wh'ich form no part of my invention. This mechanism includes a first rotor or drum 22 bearing numerals from 0 to 9 on flat. faces of the drum. Drum 22 is mounted on and driven by shaft 81 so that every minute the drum is abruptly advancedv one increment to bring the next succeeding numeral into registry with window l2, the windowI being adjacent th'e drum as may be seen in Fig. 8i

The timingindicating mechanism also includes similar rotors or drumsY 2i]l and 2 l, drum 2l bearing two series of` numerals ranging from to 5 on iiat faces of the drum, and drum 2t bearing numerals from 1 to 12. on atfaces of the drum, drums 20 and 2|r thus having the same number of iiat faces.

Drums 20 and` 2l are rotatable on shaft 8T and the operating mechanism for these drums is such that each time drum 22 makes a complete revolution drum 2l is advanced one increment, and whenever drum 2i has advanced six increments (which will of course require one hour) drum 20 will be advanced one-increment. The numerals on drumsZ and 2l which' are adjacent the numeral on drum 22 which isbrought into registry with window l2 also registry with window i2 and as will now be apparent these numerals indicate the time in hours and minutes;

In Figure 9 numeral` I5 designates a manual knob for rotating the shaft 5l' for purposes of starting the electric timing motor. Numeral It" designates a manual knob on shaft 87 which is for purposes of adjusting the setting of the time indicating mechanism.

The present embodiment of the invention has the advantage that because of the compactness of my particular timing motor and the gear train, a very small and compact clock may be constructed at low cost.

Figures 1)` and l1 disclose a further embodiment or" my invention wherein the timing unit is applied to a clock of a different type. In Figure 1l the clock is shown as having av casing ll with a glass face i2 and a back plate I3. The timing unit is very much the same as that of the previous embodiment being suitably supported in casing by sc and spacing members as shown. However, in the present embodiment the collar 'l acts on a pivoted lever Si) which is of a slightly diierent shape than that of the previous` em'- bodiment and is normally biased in a clockwise direction by a coil spring 2i). The lever 80 carries a pawl 85 which cooperates with and is arranged to rotate a ratchet wheel 83. In the present embodiment as lshown in Figure l1, knobs i5 and it are provided for purposes of starting the timing unit and for adjusting the time indicating mechanism, these knobs being exterior of back plate i3. InY the present embodiment the ratchet wheel 8S is mounted on the shaft 87 and it drives a gear train generally indicated at 25. Numeral 25 indicatesV a minute hand carried by a collar 24 which is driven at the proper speed by the gear train 25. Numeral 28 designates an hour hand mounted on the shaft 8T and which is driven at a speed so that it makes one complete revolution in twelve hours.

Figures 12` and' 13 ofthe drawings representa further modication of my invention wherein' I.

havez shown my improved timing mechanism. as applied toi a'. time switch. In thesev gures numeral ITIv designatesvv a housing for the timev switch, the housing having a hinged cover I2 providing vaccess to the interior thereof and which may be secu-red in closed position by meansof ascrew I3'. The housing Ill has-brackets I4, i5", and t6 whereby it may beV4 mounted onl a vertical wall.

The timing motor unit 50 is substantially the same as that of previous embodiments, it having windings 5t, aheore- 52 and a rotor 55V as previouslyl described. The motorof the present embodiment is of the self-startingtype as in the 'rst embodiment, there being anarmature 6i)- wit-hin the-windingsv 5+ attached toa bell-crank lever -Slwhich in turn is connected to a member 64' which is arranged tomove-vertically in a guide 65 in the same-manner as described inthe first embodiment forl imparting` an' impulse tothe rotorV when thev windings are energizedv for the purposes of starting thevv motor in operation.

In the present embodiment there isa worm gear 68 mounted` on the shaftv 5l' which drives a'pair4 of' gears at slightly diierent speeds just as in' theprevi'ous embodiments; Also asin previousV embodiments there isa reciprocatable collar 16 which actuates a push' rod I8 which extends throughV a bracket I'I, the bracket being attached to) the core 52'. Carried by the push rod" It is a; pawl which' actuat'es` a ratchet wheel' 89 mounted on the shaft 8i. The shaft 8T is' journa-lledin' bearings formed in brackets sup-` portedy by the core` 52A and its left end, as seen in Figure l2, extendsv exteriorly' of the housing H- and has a knob i9 thereon for purposes of: adjusting the position of the ratchet wheel as' will be described. Mounted on the shaft' 81 is a time indicating wheel or drum 20' bearing the numerals` 1 to 12 on its surface. The shaft' 81' makes one revolution every-twelve hours andthe drum 201 ispositioned adjacent anA opening' or' window in the casing I i so that one' of the numbers on the drum is always in registry with' the' window; Half of the ratchet wheel 86 isshaded" at its periphery and the other half is unsha'd'ed and it isv `graduated in the same' manner as theK time `dial of previous embodiments. Mounted on thev shaft 81- tothe right of the ratchetwheel 86` asiseen on-Fi'gure 12` areftwo similarcam elements 22 and 23. It will be seen thateach of these cam elements has a rise and an abrupt drop-off, theV` portions between the rise and drop-oir being of*1 uniform circularconformation. Normally these two cam elements which are adjustable on the sha-ftY 8f!" overlap each other' a certain amounti so that together theyproduce a cam contourl having a portion off' uniformr circular conformation which is of relative-ly greatery extent than the circular portion ofthe contour'of eithercam elefment alone. Numeral 2liA designates a thumb nut' on theshaft 8l adjacent the cam elements 22" and 23 and which canf be-fdrawn upsoas to tightly secure. the cam elements against a collar adjacentzthe ratchet wheel 8G, When the thumb nut. 24 isI loosened the, cam elements 22` and' 23 can be adjusted.relativelytoA eachv other tovar-y/ the. angular extent. of the cam: contour portion of uniform circular conformation produced by the.:

two cam elementstogether. In other words, the

angular distance between therise on oneV cam and the drop-off on the othercanbev adjusted; Cof--v operating withv the camelements22A and 23`is1a4 cam follower arm 25V whichfollows out the: sur-` face; of the cam' elements. The: other: end of. the:-

cam follower arm 25 is attached to a shaft 26 supported in brackets 2l and 28 at the bottom of the housing Il. Numeral 29 designates a coil spring on the shaft 26 having one end engaging the bracket 26 and the other end engaging the arm 25 and urging the arm 25 in a direction so that its end follows out the contour of the cam elements. Secured to the other end of the shaft 26 is a resilient bracket 3l) carrying a mercury switch 3|.

With the parts in the position shown the cam follower arm is adjacent a portion of one of the cam elements of smaller radius and the shaft 26 and mercury switch 3i are in a position Wherein the mercury switch is open. The cam elements are rotated in a clockwise direction as seen on Figure 13 and as will be seen, when the cam follower arm 25 follows out the rise on cam element 23 the cam follower arm and shaft 26 will be rotated in a counter-clockwise direction so as to tilt the mercury switch 3| and make contact between its electrodes which are at the left end of the mercury switch. The mercury switch will stay in this position while the cam follower arm 25 continues to follow out the contour of both of the cam elements and until it eventually drops off the'cam element 22 whereupon the mercury switch will be returned to the position shown in the drawings. As previously described, the relative duration of times during which the mercury switch is open and closed may be adjusted by manually adjusting the positions of the cam elements 22 and 23 relatively to each other. Obviously, by manually turning the knob I9 the drum 26 and ratchet wheel 86 may be adjusted to any desired position, it being possible of course to manually actuate the mercury switch in this manner.

From the foregoing descriptions of the various embodiments of my invention it will be seen by those skilled in the art that I have provided a novel and improved clock and various timing arrangements employing it. My improved gear train is advantageous in that it employs only a very small number of parts and is very compact but yet providing a very great reduction in speed. Forv these reasons, by employing my invention a very compact and inexpensive clock may be manufactured and instruments employing timing mechanisms may be built very cheaply and in very compact, neat and convenient forms. As pointed out above, my invention is very flexible in adaptation to thermostats or similar instruments requiring clock mechanisms.

` Various forms of my invention which have been disclosed are representative of some of its species and of applications to which it may be put. Numerous other forms, variations and applications which are within the scope of the invention may occur to those skilled in the art and therefore my invention Vis not to be limited by my disclosure but only in accordance with the appended claims.

I claim as my invention:

1. Mechanism of the class described comprising in combination, a pair of elements rotatable about the same axis, means for causing relative rotation between said elements, a. member movable alongr said axis, means associated with said elements for causing a backward and forward reciprocating movement of said member in response to the relative movement between said elements, a normally stationary control device engaged by said member, and connections between said device and member by which said member causes a movement of said device corresponding to the forward movement of said member.

2. Mechanism. of the class described comprising in combination, a pair of elements rotatable about the same axis, means for causing relative rotation between said elements, a member movable along said axis, means associated with said elements for causing a backward and forward'reciprocating movement of said member in response to the relative movement between said elements, a ratchet wheel, and a normally stationary pawl therefor positioned to be intermittently actuated by said member upon, and as a direct result of, its reciprocation.

3, Mechanism of the class described comprising in combination, a pair of elements rotatable about the same axis, means for rotating said elements at constant but different speeds, a cam rotated by one of said elements, a cam follower rotated by the other of said elements whereby said cam follower is given a reciprocating movement longitudinally of said axis of rotation upon rotation of said elements, and a normally stationary control device positioned by said cam follower as a result of its longitudinal movement but independently of its rotary movement.

4. Mechanism of the class described comprising in combination, a pair of elements rotatable about the same axis, means for rotating said elements at constant but different speeds, a cam rotated by one of said elements, a cam follower rotated by the other of said elements whereby said cam follower is given a reciprocating movement longitudinally of said axis of rotation upon rotation of said elements, a ratchet wheel, and a normally stationary pawl therefor positioned to be intermittently actuated by said member upon, and as a direct result of, its reciprocation.

5. Mechanism of the class described comprising in combination, a pair of gears mounted to rotate about the same axis, said gears having an unequal number of teeth, a worm gear adapted to mesh with each of said pair of gears for driving them whereby they are rotated at slightly different speeds, a member movable longitudinally along said axis of rotation, means associated with said pair of gears for causing a backward and forward reciprocating movement of said member upon relative rotation between said pair of gears, a normally stationary control device engaged by said member and connections between said device and member by which said member causes a movement of said device corresponding to the forward movement of said member.

6. Mechanism of the class described comprising in combination, a pair of gears mounted to rotate about the same axis, said gears having an unequal number of teeth, a worm gear adapted to mesh with each of said pair of gears for driving them whereby they are rotated at slightly different speeds, a member lmovable longitudinally along said axis of rotation, means associated with said pair of gears for causing a backward and forward reciprocating movement of said member upon relative rotation between said pair of gears, a ratchet wheel, and a normally stationary pawl therefor positioned to be intermittently actuated by said member upon, and as a direct result of, its reciprocation.

7. Mechanism of the class described comprising in combination, a pair of gears mounted to rotate about the same axis, said gears having an unequal number of teeth, a worm gearin mesh with both of said pair of gears for rotating them simultaneously at unequal speeds, a cam rotated by a first of said pair of gears, a cam follower rotated by the second of said pair of gears, said p cam follower being movable longitudinally of said axis of rotation and being biased into engagement with said cam, a ratchet wheel, and a pawl mounted on a stationary pivot and positioned 

